Feeding organization for grinding ball making machine

ABSTRACT

A bar feeding organization for ball machines wherein grinding balls are produced by passing a bar between tapered, helically grooved rolls which progressively cut the bar into short lengths and roll these short lengths into balls. A heating furnace accommodates a plurality of pieces of bar stock, which may in turn be aligned with an insulated feed tube. The bars are fed into this insulated feed tube, and a pinch roll arrangement at the exit end of the feed tube engages the bar and starts it rotating. The pinch roll arrangement is mounted for movement toward and away from the ball machine, whereby to feed a rotating bar into the rolls of the ball machine. By virtue of the feed tube, whipping about the bar stock in process is prevented, too rapid cooling of the trailing end of the bar stock is avoided, so that bar stock of great length may be used with safety.

United States Patent [191 Pardo FEEDING ORGANIZATION FOR GRINDING BALL MAKING MACHINE [75] Inventor: Oscar L. Pardo, Middletown, Ohio [73] Assignee: Armco Steel Corporation,

Middletown, Ohio 22 Filed: Feb. 5, 1973 21 Appl. No.: 329,551

[52] US. Cl. 72/69, 29/1484 B, 72/98, 72/100, 72/128 [51] Int. Cl B2lb 27/06 [58] Field of Search 72/43, 69, 71, 98, 100, 72/128; 29/1484 B [56] References Cited UNITED STATES PATENTS 388,565 8/1888 Kempster 72/69 1,525,222 2/1925 Canda 72/69 2,091,340 8/1937 Sutherland. 72/128 2,409,649 10/1946 Wells 72/71 2,937,436 5/1960 Butler et al. 72/128 3,478,556 11/1969 Baumgartner et al. 72/185 Q N R Aug. 6, 1974 Primary Examiner-Charles W. Lanham Assistant Examiner-James R. Duzan Attorney, Agent, or Firm-John W. Melville; Albert E. Strasser; Stanley H. Foster ABSTRACT A bar feeding organization for ball machines wherein grinding balls are produced by passing a bar between tapered, helically grooved rolls which progressively cut the bar into short lengths and roll these short lengths into balls. A heating furnace accommodates a plurality of pieces of bar stock, which may in turn be aligned with an insulated feed tube. The bars are fed into this insulated feed tube, and a pinch roll arrangement at the exit end of the feed tube engages the bar and starts it rotating. The pinch roll arrangement is mounted for movement toward and away from the ball machine, whereby to feed a rotating bar into the rolls of the ball machine. By virtue of the feed tube, whipping about the bar stock in process is prevented, too rapid cooling of the trailing end of the bar stock is avoided, so that bar stock of great length may be used with safety.

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v. [I w L V FEEDING ORGANIZATION FOR GRINDING BALL MAKING MACHINE BRIEF SUMMARY OF THE INVENTION In the manufacture of steel grinding balls in a ball machine of the type disclosed in Italian Pat. Nos. 584,907 and 593,542, preheated bar stock is fed axially between a pair of tapered, helically grooved rolls. These rolls progressively nip off short pieces of the bar stock and roll them into balls and discharge them ready for subsequent heat treatment. These machines perform very well, but they are subject to certain drawbacks.

It is impossible to use long lengths of bar stock to feed these machines. It has been found that the cooling of the trailing end of the piece of stock limits the length of stock which can be used. Bearing in mind that the stock fed to the ball machine is red hot and that it is initially engaged at its leading end by the rolls which start the stock rotating, a twist tends to develop in the stock as a result of this sudden rotational acceleration. If the bar is of substantial length, its inertia to rotation will increase the twisting effect to the extent of producing failure by torsion shear. Furthermore, even if the bar stock does not fail, it tends to flip around and vibrate, thus enhancing the risk of failure and creating a danger to personnel and equipment.

With the foregoing problems in mind, it is an object of the present invention to provide an apparatus which makes possible the use of long pieces of bar stock without the danger of encountering torsion shear of the stock, without permitting the trailing end of the stock to cool down below working temperature, and without danger to personnel or equipment.

Briefly, there is provided a conventional bar furnace. An insulated feed tube is provided to surround the hot bar during its travel from the bar furnace to the ball machine. At the exit end of the feed tube there is disposed a pinch roll arrangement which engages the leading end of the bar emerging from the feed tube. This arrangement is movable axially of the bar, and means are provided to start the bar rotating; thus the bar is already rotating when its leading end enters the ball forming rolls.

The structures above outlined provide for maintaining the temperature of the bar all the way to its trailing end, for gradually initiating rotation of the bar and reducing or eliminating the inertia to rotation which would have to be overcome by the ball forming rolls,

and for the prevention of excessive slipping of the bar prior to entering the ball forming rolls.

BRIEF DESCRIPTION OF THE SEVERAL FIGURES OF THE DRAWING FIG. I is a vertical cross sectional view of an apparatus according to the invention.

FIG. 2 is a plan view of the same.

FIG. 3a is a diagrammatic view taken on the line 3--3 of FIG. 2 showing the pinch roll assembly in one position.

FIG. 3b is a diagrammatic view similar to FIG. 3a showing another position.

FIG. 4 is an end elevational view of the bar furnace as seen from the line 4-4 of FIG. 1.

DETAILED DESCRIPTION The ball forming machine, per se, does not constitute a part of this invention and will therefore not be described in detail. In the drawings there are shown only the counter-rotating, tapered, helically grooved ball forming rolls and these are indicated at 10 and 11. The pass line for these rolls is indicated at 12.

A generally conventional bar heating furnace is indi- 0 cated at 13. The furnace is of a size to accommodate a plurality of bars 17. The bars may be fed into the furnace by an operator at the entrance end of the furnace with the assistance of the pinch rolls 18. Since the bars will be fed into the furnace at different times, the bars in the furnace will be at different temperatures. A selected bar which has attained a proper temperature, may be brought into alignment with the feed tube 20. The feed tube 20 is aligned with the pass line 12 mentioned above and extends from adjacent the exit end of the furnace to a pinch roll assembly indicated generally at 21. In order to guide a bar from the furnace into the feed tube, a flared guide 22 is provided and a pair of transverse pinch rolls 23.

When a particular bar in the furnace is ready for processing, the operator will simply feed another bar by means of the pinch rolls 18 behind the bar which is to be fed to the ball forming machine and this will push the leading end of the heated bar through the flared guide 22 into the bite of the pinch rolls 23, which will then feed the heated bar into the insulated feed tube 20. The insulated feed tube will be of a length to accommodate the longest length of bar stock which the apparatus is expected to handle and may be as much as about 22 feet (6.7 meters) in length. Its inside diameter will be only slightly larger than the largest diameter bar stock to be operated upon by the ball forming machine. The tube 20 is thoroughly insulated as is well known in the art andfor most purposes it will maintain the bar at a forging temperature until its trailing end enters the ball forming rolls. If it fails to maintain this temperature, it is of course possible to preheat the bars a few degrees higher in the furnace 13 or alternatively the feed tube 20 may be heated by electrical or other suitable means as is well known in the art.

To feed the heated bar stock from the feed tube 20 into the rolls l0 and 11, there is provided the pinch roll assembly indicated generally at 21. As best seen in FIGS. 3a and 3b, this comprises a pair of rolls 24 at least one of which is driven by means of a prime mover such as an electric motor 25 having a fluid transmission which has an inherent slippage characteristic. An upper pinch roll is indicated at 26 and means, such as a hydraulic cylinder 27, are provided for raising and lowering of the pinch roll 26.

As best seen in FIG. 1, the pinch roll assembly is mounted upon wheels 28 which are arranged to ride on tracks 29 so as to be capable of movement from the exit end of the feed tube, as shown in solid lines in FIG. 1, to the dotted line position in FIG. 1 adjacent the entrance end of the ball forming rolls 10 and 11. The dotted line position is indicated at 21a. Preferably, a bar guide flared similar to the guide 22 is provided at 30 which may be mounted on idler rolls or other suitable means to insure rotation so as to minimize frictional effects from the rotating rod, and to insure a proper entry of the bar into the rolls 10 and 11.

As a result of the fluid transmission mentioned above, the pinch roll assembly gradually imparts rotational acceleration to the hot bar and preferably the bar will be rotating at the speed of rotation it will achieve when it enters the rolls l and 11, although this is not absolutely necessary. However, the rotational feed of the bar should be quite close to the final rotational speed in the ball forming machine.

Translation of the assembly 21 may be accomplished by means of hydraulic cylinders with suitable limit switches as is well known in the art, and the translation speed may be the same or slightly less than the linear speed of the bar as it goes through the ball machine.

The upper pinch roll 26 may also be actuated by suitable limit switch arrangements so that the upper roll engages the bar as it emerges from the feed tube and disengages just after the bar enters the rolls l0 and 11. As the bar is gripped by the pinch roll assembly, movement of the assembly toward the ball machine is initiated and by means of limit switches, the movement to the right in FIG. 1 is stopped and the upper pinch roll 26 is raised to release the bar whereupon the assembly 21 returns to the solid line position of FIG. 1. The necessary circuitry for accomplishing these timed relationships will be obvious to one skilled in the art, and they have not been described in detail herein.

The rolls 24 and 26 preferably have a flat and wide profile so as to have a sufficient grip on the rotating bar to impart the necessary axial force to feed it into the ball machine; but they must be wide enough so that the pinching pressure will not cause metal flow in the hot bar and reduce the diameter of the bar at the point of contact.

The metallic portion of the feed tube 20 may be of expendable heavy duty black steel pipe so that it may be replaced easily and inexpensively.

In the operation of the device, an operator will start a new bar into the pinch roll 18 to push a suitably heated bar 17 into the transfer pinch rolls 23. These rolls are preferably driven continuously since it may be that short bars will be processed along with long bars and it will be necessary for a new hot bar to always push the bar just ahead of it in the feed tube. Provision is made for adjusting the speed of the pinch rolls 23 and preferably the bar in the feed tube 20 will move slightly slower than the speed at which the bar in the ball machine is moving, so as to provide a gap between bars and make it possible to use a feed sensor control signal for the pinch roll assembly 21. Means will of course also be provided to open and close the pinch rolls 23 so that new bars may be gripped after the trailing end of a preceding bar has been discharged into the feed tube. Means may also be provided for reversing the rotation of the pinch rolls 23 so that a hot bar may be returned to the furnace if necessary, and of course an over-ride switch may be provided in case of some emergency.

it should also be noted that the travel of the pinch roll assembly 21 between its positions shown in solid and broken lines in FIG. 1 should be kept to a minimum so as to minimize the length of time that an unconfined bar is exposed, so as to keep heat loss and vibration effects to a minimum.

It will be understood that numerous modifications may be made without departing from the spirit of the invention. No limitation not specifically set forth in the claims is intended and no such limitation should be implied.

I claim:

1. A feeding organization for feeding bars from a bar furnace to a ball forming machine having ball forming rolls, comprising:

a. a thermally insulated feed tube in close communication with said bar furnace, and axially aligned with the pass line of said ball forming rolls,

b. a pinch roll arrangement for feeding bars from said feed tube into said ball forming rolls, and

c. said pinch roll arrangement having means to initiate, at least, rotation of said bars in the direction in which they will be rotated by said ball forming rolls,

whereby heat loss in a bar in passing between the furnace and the ball forming machine is minimized, and whereby failure due to torsion shear of the hot bar is avoided.

2. A feeding organization according to claim 1, wherein a pair of pinch rolls is provided at the entrance end of said feed tube to feed bars from the said furnace into the said feed tube.

3. A feeding organization according to claim 2, wherein a bar guide is disposed ahead of said pair of pinch rolls to assure that the bar enters the feed tube correctly.

4. A feeding organization according to claim 1, wherein said pinch roll arrangement comprises a pair of lower rolls and an upper roll, the axes of said rolls being parallel to the feed tube, one, at least, of the lower rolls being driven, and means for raising and lowering the rolls to grip or release the bar, said arrangement being mounted for movement as a unit between the exit end of the feed tube and the ball forming rolls; whereby as the leading end of a bar enters said arrangement, rotation of the bar is initiated, and the rotating bar is pulled from said feed tube and thrust into said ball forming rolls.

5. A feeding organization according to claim 4, wherein the lower roll drive incorporates a fluid drive transmission between the driving means and the roll, whereby the inherent slippage characteristic of the transmission accomplish a gradual rotational acceleration.

6. A feeding organization according to claim 4, wherein a bar guide is disposed just before the ball forming rolls to insure that the said pinch roll arrangement feeds the bar correctly into the ball forming rolls.

minimize frictional effects from the rotating rod. 

1. A feeding organization for feeding bars from a bar furnace to a ball forming machine having ball forming rolls, comprising: a. a thermally insulated feed tube in close communication with said bar furnace, and axially aligned with the pass line of said ball forming rolls, b. a pinch roll arrangement for feeding bars from said feed tube into said ball forming rolls, and c. said pinch roll arrangement having means to initiate, at least, rotation of said bars in the direction in which they will be rotated by said ball forming rolls, whereby heat loss in a bar in passing between the furnace and the ball forming machine is minimized, and whereby failure due to torsion shear of the hot bar is avoided.
 2. A feeding organization according to claim 1, wherein a pair of pinch rolls is provided at the entrance end of said feed tube to feed bars from the said furnace into the said feed tube.
 3. A feeding organization according to claim 2, wherein a bar guide is disposed ahead of said pair of pinch rolls to assure that the bar enters the feed tube correctly.
 4. A feeding organization according to claim 1, wherein said pinch roll arrangement comprises a pair of lower rolls and an upper roll, the axes of said rolls being parallel to the feed tube, one, at least, of the lower rolls being driven, and means for raising and lowering the rolls to grip or release the bar, said arrangement being mounted for movement as a unit between the exit end of the feed tube and the ball forming rolls; whereby as the leading end of a bar enters said arrangement, rotation of the bar is initiated, and the rotating bar is pulled from said feed tube and thrust into said ball forming rolls.
 5. A feeding organization according to claim 4, wherein the lower roll drive incorporates a fluid drive transmission between the driving means and the roll, whereby the inherent slippage characteristic of the transmission accomplish a gradual rotational acceleration.
 6. A feeding organization according to claim 4, wherein a bar guide is disposed just before the ball forming rolls to insure that the said pinch roll arrangement feeds the bar correctly into the ball forming rolls.
 7. A feeding organization according to claim 1, wherein said feed tube is heated.
 8. A feeding organization according to claim 6, wherein said bar guide is rotatably mounted, so as to minimize frictional effects from the rotating rod. 